Thermostatic burner control



NOV. 1, 1932. J DONOHUE 1,885,515

THERMO S TAT I C BURN ER CONTROL Filed July 50, 1929 5 Sheets-Sheet l Nov. 1, 1932. 5 AQ'J. DONOHUE THERMOSTATIC BURNER CONTROL Filed July 50, 1929 5 Sheets-Sheet 2 Iwmi'or 2 his filter .5, /ww

Nov. 1, 1932.

A. J. DONOHUE THERMOSTATIC BURNER CONTROL Filed July 30, 1929 5 Sheets-Sheet 5 Nov. 1, 1932.

A. J- DONOHUE THEBMOSTATIC BURNER CONTROL Filed July 30, 1929 5 Sheets-Sheet 4 NOV; 1, 1932. A 1 DONOHUE 1,885,515

THERMOSTATIG BURNER CONTROL Filed July 30. 1929 5 Sheets-Sheet 5 Patented Nov. 1,

PATENT. OFFICE ANTHONY J. DONOHUE, OP PHILADELPHIA, PENNSYLVANIA, A SSIG NOR TO SIMPLE! GAS PRODUCTS CORPORATION, OF DELAWARE 0F PHILADELPHIA, PENNSYLVANIA, A CORPORATION rnnnmos'ra'rrc BURNER CONTROL Application flied July 30,

This invention relates to improvements in thermostatic burner controls for atmospheric gas burners of that type wherein the supply of gas and secondary air to a burner can be automatically controlled from a remotely situated thermostat, pressurestat, hydrostat or the like or a combination of such controlling devices.

To insure the successful operation of atmospheric tities of gas and are controlled by a remotely disposed control element it is essential that the control valve functions with a quick snapping movement and that an abundance of power be available to seat the valve tightly even though deposits from gas may be present upon the valve seat.

e usual arrangement for controlling burners where large quantities of gas are consumed consists of either an electric motor connected to a quick-acting gas valve or a large diaphragm type a solenoid. Burners controlled in this manner will perform satisfactoril at normal gas pressures but are extremely likely to flash back On extinguishing durin periods when the gas pressure is low. 'Un or such conditions the momentum of the gas stream issuing from the burner orifice during the short period in which the valve is closing is materially less than normal. Consequently, it frequently happens that this momentum .is insufiicient to produce a pressure in the burner head capable of forcing the air-gas mixture through the burner ports at a velocity equal to the rate of flame propagation, in which event the flame strikes back through the mixture and burns at the orifice of the burner. After such a valve closes there is generally enough unburned piping between the gas valve and the orifice to support a tiny flame for a considerable length of time and obviously if during this time'the thermostat operates to open the valve the full gas supply burns at the orifice producing carbonization tion of the burner.

It should also be understood that if the usual bi-metallic thermostatic strip or leaf is employed to directly operate the valve of a and improper operagas burners which use large quangas valve controlled by gas remaining in 1929. Serial No. 382,144.

burner control the resulting force exerted Would be insuflicient to valve and the extremely slow, creeping movement imparted would cause the burner to flash back both in lighting and extinguishing. That a quick snap-acting movement accompanied by considerable force is essential to control large quantities of gas is recognized by those familiar with the art.

Accordingly, another important object of the present invention is the production of a simple, reliable and comparativel inexpensive thermostatic burner control that will be capable of thermostatically controlling lar e capacity gas burners without the usual disadvantages associated with such controls.

A further object of the invention is the production of an apparatus of this character which will simultaneously control the flow of as and secondary air to the burner.

5 further object of the invention is the provision of a leverage system through which the movement of a thermostatic disc may be sufficiently magnified to permit a gas valve of this type to be withdrawn from its seat a distance suflicient to insure unimpeded flow of gas to the burner when in operation.

A further object of the invention is to provide a structure of this character which may be ver readily adjusted and which provides a rea il adjustable and reliable means for controlling the supply of secondary air to the burner. 4

A further object of the invention is the production of apparatus of this character which may be electrically operated on a comparatively low voltage so that the expense in connection with the installation of the necessary electrical conduit is materially reduced.

A still further object of the invention is to produce an electrically controlled apparatus of this character in which the consumption of current is materially reduced after the initialopening operation and during the period when the control position and which will provide for automatic closure of the valve in event of current failure.

A further object of the invention is to provide apparatus of this character enabling combination therewith of a simple and convalve remains in open properly seat the venient manual control through which the burner may be hand-controlled in event 0 current failure and which is automatically disengaged when the control. circuit is again energized.

Another object of this invention is to produce a thermostatic burner control capable of successful operation during periods of wide voltage fluctuations in. current supply. A further object of the invention is the pro duction of a thermostatic burner control which will effectively prevent burner flash back and the subsequent burning'of gas at the burner orifice, two disadvantages commonly associated with the operation of atmos pheric gas burners under thermostatic control especially when the gas pressures are low.

A further object of the invention is to provide an absolutely silent burner cut-off eliminating the usual burner pop occurring when atmospheric gas burners are extinguished particularly when the pressures are low.

These and'other objects I attain by the construction shown in the accompanying drawings wherein, for the purpose of illustration, 1 have shown a preferred embodiment of my invention and wherein:

Fig. 1 is a side elevation partially in section of a burner control constructed in accordance with my invention, the dotted line position indicating the operation of the apparatus in controlling the admission of secondary air;

Fig. 2 is a front elevation thereof;

Fig. 3 is an enlarged side elevation partially in section of the control element;

Fig. 4 is a section on line 4-4of Fig. 3;

Fig. 5 is a section on line 55 of Fig. 3;

Fig. 6 is a section on line 6-6 of Fig. 3; and

Fig. 7 is a schematic wiring diagram showingl the connections employed with the contro Referring now more particularly to the drawings, the numeral 10 generally designates a main casing which is preferably axially aligned with a gas burner 11 having associated therewith the usual primary air shutter 12. This shutter in accordance with my invention is supported by a tubular housing 13 secured to the casing 10 and sealed therefrom by an intervening flexible diaphragm 14 having its edges included in the connection between the housing 13 and casing 10. The inner end of housing 13 mounts the usual burner type of burner orifice 15 and the-adjacent portions of the housing are formed asa valve casing 16 affording an interiorly disposed seat 17 about the orifice mounting. Slidable in bearings 18 provided in the hous-' ing is a valve stem 19 which has engagement with one of said bearings preventing rotation thereof as indicated at 20. The inner'end of this valve stem has secured thereto a ball head valve 21 for co-action with the seat, the con- 1,es5,515 I nection 22 between the valve and stem being preferably of such character that a slight movement of the valve with relation to the stem may be 'had. This stem extends through and is rigidly secured to the diaphragm 14 as indicated at 23. \Vithin the housing 10' at opposite sides thereof upon pivots 24 and 25 levers 26 and 27 are pivoted, lever 26 being pivotally connected with the lever 27 at a point adjacent the pivot 25 of this lever as indicate-d at 28. Lever 27 has its free end projet-ting through a slot 29 formed in the wall of housing 10 and intermediate its ends and within the housing is slotted as at 30.

Secured to the outer end of stem 19 is a yoke 31 having a pivot element 32 in the form of a shoulder screw extending through slot 30 of lever 27.

The outer end of housing 10 is open and has secured thereto a removable cap or cover plate 33, the connections between the casing and cover plate securing in position therebetween a ring 34, to the inner edge of which is secured the peripheral edge of a dished metallic thermostat disc 35. The central portion of this disc is apertured and receives in the aperture thereof a reduced portion of a collar 36 surrounding an actuating shaft 37 mounted in abearing 38 formed in the cap for axial movement. (Rotative' movement of this cap is prevented through a tongue 39 engaging in a slot formed in the outer end of the actuating shaft, which tongue is carried by a screw plug 40 for the outer end of bearing 38. The inner end bored and interiorly threaded for the reception of the threaded outer end of a shaft extension 41.- The inner end of this shaft is directed through an opening formed in lever 26, this lever at opposite sides thereof in alignment with said opening being provided with knifebearings 42 for engagement with fixed stops 43 carried by the shaft extension and of whi. h one forms a means for rotatably adjusting the shaft extension to thereby determine the effective length of shaft 371 A lock nut 44 upon the shaft extension and engaging the end of shaft 37 insures the integrity of the adjustment.

The convex face of the thermostatic element 35 has suitably secured thereto a pair of heating resistances 45 and 46, of which the resistance 46 is a relatively low wattage. It will be obvious that by employing the resistance 45 to heat thermostatic element 35 to an extent causing the operative movement or snap characteristic to said thermostat and then transferring the heating to the resistance 46 the thermostatic element may be readily held in its operated position thus providing fora quick operation of the thermostatic element and an economical maintenance thereof in its operated position.

To control the operation of the thermostat I preferably provide an arrangement such as it against its seat. It will 1 a thermal through a that the stem is situated thermostat.

schematically designated in Fig. .7. In this figure the numeral 47 designates a remotely situated thermostatically, pressurestatically or hydrostatically-operated switch, or if desired a switch controlled by an operation of a plurality or a combination of such devices. One terminal of this switch is connected to a terminal 48 common to the resistances and 46 and the opposite terminal of switch 47 is electrically connected to one switch element of each of a pair of switches indicated generally at 49 and 50. The remaining terminals of switches 49 and 50 are connected to the resistances 45 and 46 respectively. Switches 49 and 50 are controlled by the movement of shaft 37. In the present instance I have disclosed the switches 49 and 50 as comprising the switch elements of a double circuit mer- V cury switch 51 mounted in a saddle 52 which is pivotally supported as at 53 from the wall of casing 10. Saddle 52 has a stem or projection 54 engaging in a slot 55 formed in a plate 56 carried by yoke 31, this slot being disposed at an angle to the axis of the stem so that when the stem 19- is reciprocated saddle 52 and the mercury switch 51 will be oscillated to cause the mercury of the switch to alternately close the contacts of switches 49 and 50. The flexed thermostatic element 35 in its normal position, which corresponds to the closed position of valve 4, is so positioned that the contacts of switch 49 accordingly, when remotely 47 closes circuit resistance element 45 will be energized rapidly heating thermostatic element 35 to cause an operation thereof.

As is well known to those familiar with the art that a flexed thermostatic element due to its construction stores latent energy .during change until the predetermined temperature is reached whereafter this energy is suddenly released in considerable force short distance. This force through shaft 37, lever '26, lever 28 and yoke 31 is transmitted to stem 19 with the result given a relatively long and comparatively strong thrust moving the ball valve 21 into and out of engagement with its seat and cutting off and turning on the supply of gas to the burner in response to remotely Due to the rapid action of the valve, back flash is prevented because the momentary low gas pressures between the valve and orifice are completely eliminated together with the consequentloss of momentum in the gas stream issuing from the orifice immediately before the burner is extinguished. For very similar reasons the concussion or pop usually associated with the extinguishing of a burner of this type is also eliminated.

to the completion of flexing of disc 35 so that the tension of the disc will be applied to hold also noted that the cap which'lever is 55a and the outer are closed and, situated switch b It will be obv'il ous that the ball head valve 21 must seat prior f This feature of the construction is important in that the sensitivity of such discs is in creased where they are held under tension preventing completion of the flexing movement and the resistance of the disc to the action of the heating elements is much more rapid-where this arrangementis employed.

In order that manual control of the burner may be had in event of failure of electrical connections or supply and at the same time the control may be immediately replaced under electrical control upon re-establishment of normal conditions, I pivot within the cap 33 as at 54a, a lever 55a which projects through a slot 56 formed in the side wall of slotted as at 57 for the passage of shaft 37. Pivoted to this lever as at 58 and having its terminal portion extending through the slot 56 is a trigger 59, a tail 60 of which is connected with lever 55a by a spring 61 tending to constantly urge this tail upwardly. Carried by the tail is an adjusting screw 62 adapted to co-act with a stop en this movement is' again 63. Directed through shaft 37 between lever wall of the cap is a pin 64 which is engaged by lever 55a when the outer end thereof is moved in the direction of the arrow of Fig. 3 to thereby cause a movement of shaft 37 corresponding to that produced y actuation ofthe thermostatic element 35.

en lever 55a is set theadjusting screw 62 engages behind stop 63 preventing its return movement, the frictional engagement of thls screw with the stop preventing elevation of the trigger tail by the spring 61. Adjust ment of the screw is made such that the throw I imparted to shaft 37 imparted by thermostatic element 35 with the result that upon-re-establishment of electrical connections the thermostatic element will be operated and in its 64 from lever 55a thus reducing the strain placed against the stop 62 by the-natural resiliency of the thermostatic element and permitting spring 61 to release the trigger and again place the. device on electrical operation.

In order that a control of the admission of secondary air may be accomplished by the apparatus above described, I mount the burn er 11 through a boiler base 65 having a secondary air opening 66controlled by a door 67 pivoted as at 68. This door is linked as at 69 with the outer endof lever 27, the link 69 having stops 70 at least one of which is ad- 'justable to permit regulation of the time and extent of secondary air admission. It will of course be understoodthat housing 13 will lave associated therewith a suitable means or supplying gas thereto as indicated by the conduit 71 and a therein. Casing 10 and its cap 33"through slots 29, 56 and through suitable additional is slightly less than thatoperation will release pin manual control valve 72 openin s 7 3 formed in the cap admits sufficient air tothe thermostatic element 35 to insure a rapid restoration thereof to its normal or closed position when the electrical heating elements become inactive.

As the construction illustrated is obviously capable of considerable range of change and modification without in any manner departing from the spirit of my invention, I do not wish "to be understood as limiting myself thereto except as hereinafter claimed.

I claim:

1. In a thermostatic valve control, a valve, a seat' therefor, a dished bi-metallic disc, electrical heating means therefor including heating units of varying intensities, a circuit for one of said units including a remotely disposed switch, a connectionb'etween saiddisc and the valve shifting the valve to unseat the same as the disc moves from one to another of its positions and-means operated by shifting of the valve from one to the other of its positions for substituting in said circuit the other of the heating units.

2. In a thermostatic valve control, a valve, a seat therefor, a dished-disc-type thermostat, a pair of electrical heating elements of different intensities for heating said thermostat, a circuit therefor and means operatedby flex ing of-said disc for alternately seating and unseating the valve and for alternately connecting said heating elements in said circuit.

3. In a thermostatic valve control, a dished bi-metallic disc, a valve, a seat therefor and leverage I connecting said disc and valve multiplying the movement of the disc as imparted to the valve to thereby provide operative movement of the valve into and out of engagement with its seat, heating elements for the disc and means operated by the valve for alternately establishing circuits for the heating elements as the valve moves into and out of engagement with its seat.

4. In a thermostatic valve control, a valve, :1 seat therefor, a dished-disc-type thermostat, a pair of electrical heating elements of different intensities 'for heating said thermostat,'a

circuit therefor and means operated by fleX- 'ing of said disc for alternately seating. and

unseating the valve and for alternately connecting said heating elements insaid circuit, the circuit of said heating elements including a remotely disposed thermo-electric switch.

5. In a burner control. for gas burners, agas inlet chamber having an outlet orifice and provided immediately adjacent said orifice'with a valve seat, a valve movable into and out of engagementwith said seat and thermostatic means for movlng the valve into and out of engagement with its seat operating to shift the valve from one to the otherjof such positions instantaneously and manually operable means for shifting the valve out of engagement with its seat.

6. In a thermostatic valve control, a valve,

a seat therefor, a dished bi-metallic disc, electrical heating means therefor including heating units of varying intensities, a circuit for one of said units, a connection between said disc and the valve shifting the valve to unseat the same as the disc moves from one to another of its positions and means operated by shifting of the valve from one to the other of its positions for substituting in said circuit the other of the heating units.

7 In a thermostatic valve control, a valve, a seat therefor, a dished-disc-type thermostat, a pair of electrical heating elements of different intensities for heating said thermostat, a

circuit therefor and means operated by fiexing of said disc for alternately seating and unseating the valve and for alternately connecting said heating elements in said circuit, the circuit of said heatingelements 1ncluding a remotely disposed switch.

ANTHONY J DONOI-IUE.

ICS 

